1. Field of the Invention
This invention relates to adapters for electrical connectors and, more particularly, to an adapter for electrically and mechanically coupling the terminal end of a pacemaker lead of one size to a pacemaker lead receptacle of another, larger size.
2. Description of the Related Art
Cardiac pacemakers, sometimes referred to as "pacemakers", are electrical devices that function to regulate the pace of the heartbeat. These vital therapeutic devices are surgically implanted in the patient's body, where they may remain for years. A typical implanted pacemaker operates by furnishing, through an electrical lead attached to the ventricle of the heart, stimulation pulses which the heart is not providing.
The pacemaker includes one or more plug-type receptacles into which the terminal electrode assembly of the electrical lead may be inserted when the pacemaker is implanted. The electrode is typically held in place in the plug receptacle of the pacemaker by a connector block and a set screw. This retaining set screw may be loosened to permit withdrawal of the terminal electrode assembly from the plug receptacle of the pacemaker, as, for example, when the pacemaker is to be replaced.
The terminal electrode assembly of the heart-stimulation leads customarily comes in different sizes. Those of more recent construction are undersized relative to earlier models. Likewise, the pacemaker receptacle which receives the terminal electrode assembly of the heart-stimulation leads comes in different sizes and varies significantly between manufacturers. In view of the fact that the installed heart-stimulation lead generally lasts longer than the cardiac pacemaker, it would be advantageous to be able to re-use the lead by adapting it to any given pacemaker model, independent of the particular size jack for the heart lead terminal electrode assemblies. This goal can be achieved by providing an adapter which is of the proper size to plug into the pacemaker receptacle and at the same time receive the implanted lead terminal electrode in a manner which establishes a reliable mechanical and electrical connection between the lead and the pacemaker.
One such adapter is disclosed in U.S. Pat. No. 4,583,543 of Peers-Trevarton. The device of that patent, however, is relatively complex in structural design, constituting a separate receptacle for the undersized terminal electrode assembly of the heart lead and a corresponding separate adapter terminal electrode assembly to couple into the full size pacemaker jack. Essentially, the adapter is constructed with the portion which couples to the pacemaker being configured like the large size terminal electrode assembly for which the pacemaker is designed.
What is presently desired is a simplified adapter which provides a match between the disparate sizes of the lead terminal electrode assembly and the pacemaker receptacle while facilitating the integrity of the connection between the pacemaker receptacle and the undersized terminal electrode assembly of the heart lead. The adapter of the present invention fulfills this need as a device which is easier and more economical to manufacture than those which are known in the prior art, as well as being at least as reliable in use.